Method and apparatus for display image adjustment

ABSTRACT

Method and apparatus for display image adjustment is described. More particularly, handles associated with polygon vertices of a polygon rendered image are provided as a graphical user interface (GUI). These handles may be selected and moved by a user with a cursor pointing device to adjust a displayed image for keystoning, among other types of distortion. This GUI allows a user to adjust a projected image for position of a projector with respect to imaging surface, as well as for imaging surface contour, where such contour may be at least substantially planar, cylindrical, or spherical and where such contour may comprise multiple imaging surfaces. This advantageously may be done without special optics or special equipment. An original image is used as texture for rendering polygons, where the image is applied to the rendered polygons.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 10/185,764filed on Jun. 27, 2002 now U.S. Pat. No. 6,963,348. This applicationclaims benefit of U.S. Provisional Patent Application Ser. No.60/384,663, entitled “Method and Apparatus for Display ImageAdjustment,” filed May 31, 2002 which is herein incorporated byreference.

FIELD OF THE INVENTION

The present invention relates generally to method and apparatus fordisplay image adjustment, and more particularly to method and apparatusfor screen display or projected image adjustment to adjust for geometricdistortion.

BACKGROUND OF THE INVENTION

Anyone who has ever viewed an image on a television set, a computermonitor, a projection screen or other projection surface, and the like,where one corner of the image was out of alignment has experienced aform distortion, namely, a geometric distortion called “keystoning” or“keystone” geometric distortion. Keystoning is where an image is out ofalignment, conventionally at one or more of the corners, of the imageproducing a trapezoidal or trapezoidal-like shape.

Computer monitors and televisions sets conventionally come withmechanisms for manually adjusting a display screen image, not only atthe corners but also top and bottom side adjustments and left and rightside adjustments. However, these adjustments conventionally requireusing multiple adjustment modes, where an adjustment in one mode mayaffect another adjustment in another mode. This leads to a timeconsuming iterative approach to bring a display image into alignment.

Iterative adjustment for image projectors conventionally involves movingthe projector itself. Thus, a projector often occupies a central pointin a room, where leg adjustment screws are used to adjust to a supportsurface on which the projector is located. The projector lens is thusaligned to be at least substantially parallel with a projection surface.Adjusting position of a projector conventionally is an iterativeapproach where one adjustment affects another. An additional annoyanceis having a projector in the way of a presenter and attendees, as theprojector conventionally is centered to the projected image to minimizedistortion. If a projector is not on-axis with respect to a projectionsurface (i.e., the direction of the projection is not perpendicular tothe screen), keystoning may result.

Modern digital projectors have keystone correction allowing for“squaring up” a projected image when projecting off-axis. However, mostof these corrections are optical adjustments and not image adjustments.Accordingly, off-axis angle is limited owing to manufacturing cost ofmore exotic lenses. Still others have suggested warping of an image tocompensate for keystoning. However, such approaches conventionallyinvolve addition of a camera to sense a displayed image or require datainput to determine position of a displayed image. Moreover, such systemsinvolve special circuitry and/or complex software to warp an image tocorrect for keystoning.

Furthermore, projecting an image off-axis to a screen or imaging surfacecan have effects other than keystoning, such as anisotropic or aspectratio geometric distortion. An example of anisotropic geometricdistortion is text that progressively expands vertically, namely, anunequal image display above and below a horizontal optical axis.Anisotropic distortion limits use of off-axis projection, even though itmay be desirable to position a projector off-axis in order to have moredistance from a projection surface to project a larger image.

Accordingly, it would be desirable and useful to provide method andapparatus for display image adjustment that is more intuitive for a userand costs less than optical adjustment or prior image warp techniques.Additionally, it would be desirable and useful if such method andapparatus enhanced ability for off-axis projection.

SUMMARY

The present invention provides method and apparatus for adjusting animage, in particular a projected image. The image can be the desktopdisplay of a computer, including that of various Microsoft Windowsoperating systems. Because it is not always feasible or desirable tohave a projector perpendicular and centered to a screen, a graphic userinterface (GUI) is provided to facilitate adjustment of the projectedimage when the projector is off-axis or not centered with respect to thescreen. In essence, the GUI enables a user to move one or more cornersor sides of the projected image in order to convert a pincushioned ortrapezoidal projected image into a rectilinear projected image. Suchadjustment by a user may be done in less than a minute. Additionally, anembodiment of the GUI enables the user to move the center of theprojected image to adjust for anisotropy. An aspect of the presentinvention is a GUI for reducing distortion in a projected image. The GUIcomprises handles projected with the projected image, where the handlesare associated with vertices of the projected image and are selectableand moveable by a user for adjusting the projected image.

Another aspect of the present invention is a method for reducingdistortion in a displayed image. Image content is obtained and stored asa texture having a set of texels. The image content is applied as atexture to at least one polygon having vertices associated with texturecoordinates in the texture. The projected image is created by renderingthe polygons with the image applied as a texture. The rendering can bedone with a three-dimensional (3D) graphics pipeline. In the GUI atleast one handle related to a vertex of the vertices is displayed withthe displayed image and moved to adjust the displayed image. Location ofthe at least one handle is updated in response to movement of the atleast one handle. The vertex is changed in response to the location ofthe at least one handle update, texture coordinates of the set oftexture coordinates are changed in response to the vertex change; andthe displayed image is changed in response to change of the texturecoordinates of the set of texture coordinates for adjustment of thedisplayed image.

Another aspect of the present invention is a method of correcting adistortion in a displayed image. Image content is obtained and stored asa texture. Polygons for the image content are rendered, where eachpolygon of the polygons has vertices at least some of which areassociated with texture coordinates within the texture. Handles for thedisplayed image associated with the image content and with the at leastsome of the vertices are displayed. Locations of the handles affectingthe at least some of the vertices associated with the handles arereceived, as the handles are moveable to change the displayed image.

Another aspect of the present invention is a method for counteractingdistortion of a displayed image. Image content is obtained. Pixel valuesfor the image content are written to an off-screen medium. Polygonsusing the image content written to the off-screen medium are rendered asa texture, and moveable vertices associated with the polygons areprovided, where the vertices are associated with texture coordinateswithin the texture and are moveable for counteracting distortion of thedisplayed image.

Another aspect of the present invention is a GUI for reducing distortionin a displayed image. Objects are displayed with the displayed image.The objects are associated with vertices of the displayed image and areselectable and moveable by a user for adjusting the displayed image.

Another aspect of the present invention is a method for associatingpositions. Image content is provided and displayed as a screen displayimage. The image content is graphically processed by mapping the imagecontent with polygons having vertices, projecting the image contentafter graphical processing as a projected display image, selecting aprojected position of the projected display image, associating theprojected position with a polygon of the polygons, and locating a screenposition relative to the polygon and the projected position.

Another aspect of the present invention is a method for determiningassociated cursor positions between user interfaces. A first userinterface and a second user interface are provided. The second userinterface is a graphically processed version of the first userinterface. Map coordinates are associated with first positions in thefirst user interface, and vertex locations are associated with secondpositions in the second user interface. A first cursor position in thesecond user interface is obtained from the second positions, and the mapcoordinates are processed using the vertex locations and the cursorposition to determine from the first positions a second cursor positionin the first user interface.

Another aspect of the present invention is a method for determiningassociated cursor positions between user interfaces. A screen displayuser interface is provided and graphically processed to provide aprojected user interface with vertex locations. Map coordinates areassociated with screen display positions. A projected cursor position ofthe projected user interface is obtained from the vertex locations, andthe map coordinates are processed using the vertex locations and theprojected cursor position to determine from the map coordinates a screendisplay cursor position of the screen display user interface.

Another aspect of the present invention is a method for determining afirst cursor position. Map coordinates are associated with positions ina first user interface. Vertex locations are associated with positionsin a second user interface, where the second user interface is agraphically processed version of the first user interface. A secondcursor position within the second user interface is received, and themap coordinates are interpolated using the vertex locations and thesecond cursor position to determine the first cursor position.

Another aspect of the present invention is a portable device configuredfor displaying a graphic user interface for adjusting an image. Memoryis configured for storing the image as a texture and for storing aprogram product. The program product is configured to provide verticesfor the image and to provided handles for projection with the image andassociated with the vertices. The handles are moveable for adjusting theimage.

Another aspect of the present invention is a portable device configuredwith a method for displaying a graphic user interface. The graphic userinterface is provided to a first display and stored as a texture.Polygons are rendered, where each polygon comprises vertices at leastsome of which are associated with texture coordinates within thetexture. Handles are rendered at least some of which are associated withsome of the vertices. The rendered polygons and rendered handles aresent to a second display device. Locations of the handles are received,where the received locations affect the associated vertices therebychanging the rendered polygons.

Another aspect of the present invention is a method of providing acommon cursor on different displays. Screen image coordinates for afirst cursor are obtained. A polygon is mapped to a screen image inwhich the first cursor is located. Texture coordinates for a secondcursor are determined in response to the polygon and the screen imagecoordinates.

Another aspect of the present invention is a method for adjusting foranisotropic distortion. An unadjusted image is rendered with polygons.Vertices of the polygons associated with corners of the unadjusted imageare selected, and at least one vertex of the vertices selected is movedto provide an adjusted image. A center of the adjusted image iscalculated in response to the vertices for the adjusted image. Theadjusted image is adjusted for anisotropic distortion in response to thecenter calculated.

Another aspect of the present invention is a method for adjusting foranisotropic distortion. An image is rendered with polygons. A handlecentered to the image is rendered, where the handle moveable by a userfor adjusting the image for anisotropic distortion in response tomovement thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features, advantages andobjects of the present invention are attained and can be understood indetail, a more particular description of the invention, brieflysummarized above, may be had by reference to the embodiments thereofwhich are illustrated in the appended drawings.

FIGS. 1A through 1C are pictorial views of exemplary embodiments ofimage projection systems in accordance with one or more aspects of thepresent invention.

FIG. 1D is the pictorial view of FIG. 1C for a system portion and atop-down view of FIG. 1C for a projection portion.

FIGS. 2A and 2B are block diagrams of exemplary portions of respectiveembodiments of an image projection system of FIG. 1A.

FIGS. 3, 3A and 3B are block diagrams of an exemplary embodiment of agraphics pipelines coupled to displays in accordance with one or moreaspects of the present invention.

FIGS. 4, 5, 6 and 7 are process flow diagrams of exemplary embodimentsof display image adjustment processes in accordance with one or moreaspects of the present invention.

FIG. 8 is a process flow diagram of an exemplary embodiment of a cursortracking routine in accordance with one or more aspects of the presentinvention.

FIG. 9A is a block diagram of an exemplary embodiment of a computerscreen having a screen image displayed thereon in accordance with one ormore aspects of the present invention.

FIG. 9B is a block diagram of a projected image of the screen image ofFIG. 9A in accordance with one or more aspects of the present invention.

FIG. 9C is a block diagram of the projected image of FIG. 9B afteradjustment in accordance with one or more aspects of the presentinvention.

FIG. 9D is a block diagram of the screen image of FIG. 9A for theprojected image of FIG. 9C in accordance with one or more aspects of thepresent invention.

FIG. 9E is a block diagram of the screen image of FIG. 9A for theprojected image of FIG. 9C after toggling back to an unadjusted screenimage and after turning off an adjustment graphical user interface (GUI)in accordance with one or more aspects of the present invention.

FIG. 9F is a block diagram of the projected image of FIG. 9C afterturning off an adjustment GUI in accordance with one or more aspects ofthe present invention.

FIG. 10 is an enlarged version of adjusted polygon of FIG. 9D.

FIG. 11 is a block diagram of an exemplary embodiment of a corneradjustment GUI in accordance with one or more aspects of the presentinvention.

FIG. 12A is a planar view of a corner projection with the corneradjustment GUI of FIG. 11 and an unadjusted image in accordance with oneor more aspects of the present invention.

FIG. 12B is a planar view of corner projection with the corneradjustment GUI of FIG. 11 and an adjusted image in accordance with oneor more aspects of the present invention.

It is to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the present invention may admit toother equally effective embodiments.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth toprovide a more thorough understanding of the present invention. However,it will be apparent to one of skill in the art that the presentinvention may be practiced without one or more of these specificdetails. In other instances, well-known features have not been describedin order to avoid obscuring the present invention.

FIG. 1A is a pictorial view of an exemplary embodiment of an imageprojection system 10A in accordance with one or more aspects of thepresent invention. Image projection system 10A comprises computer system19A and projector 14. Computer system 19A comprises computer monitor 11,mouse 13, keyboard 12 and computer 18. Computer 18 comprises an imageadjustment program, described below in more detail. An image stored incomputer 18, or obtained from a network when computer 18 is coupled tosuch a network, is provided as output to projector 14. Projector 14projects such an image onto projection screen 15A for viewing projectedimage 16A. Projector 14 may be a CRT, LCD or DLP type of projector.Moreover, if projector 14 comprises computing capability described belowin more detail, projector 14 may comprise such an image adjustmentprogram.

Notably, projected image 16A is exhibiting keystoning. Adjustment toremove or reduce this distortion is described below in more detail.Projector 14 is shown off-axis with respect to a plane of screen 15A,and at an angle, α, with respect to direction of projection 9 and aground or horizontal plane 8. However, for purposes of clarity, angle,α, is shown as an angle between horizontal plane 8 and a bottom ray ofprojection hereinafter.

FIG. 1B is a pictorial view of an exemplary embodiment of an imageprojection system 10B in accordance with one or more aspects of thepresent invention. Projection system 10B comprises notebook computer 19Band projector 14. Accordingly, computer system 19A of FIG. 1A isreplaced with notebook computer 19B. Computer 19B comprises an imageadjustment program, described below in more detail. Image surfacing neednot be at least substantially planar as is projection screen 15A of FIG.1A, but may be a cylindrical surface as is image surface 15B. Contour ofan image surface, as well as angle, α, of projector 14 with respect tosuch an image surface, will have an affect on amount of distortion of aprojected image, such as projected images 16A and 16B of FIGS. 1A and1B, respectively. Moreover, it will be apparent that many other imagesurface contours may be used, including but not limited to spherical.Notably, projected image 16B is distorted. Adjustment to remove orreduce this distortion is described below in more detail. The computer19B can be incorporated into the projector 14, or vice-versa

FIG. 1C is a pictorial view of an exemplary embodiment of an imageprojection system 10C in accordance with one or more aspects of thepresent invention. Projection system 10C comprises personal digitalassistant (PDA) 17, in place of computer 18, and projector 14 forprojecting onto image surfaces 15C-1 and 15C-2. Accordingly, projectedimage 16C may be projected onto more than one imaging surface. In thisexample, projected image 16C is projected into a corner for imaging ontoimage surfaces 15C-1 and 15C-2. PDA may be connected to a network, suchas a wired connection or an over-the-air (“wireless”) networkconnection, to provide images for projecting or may comprise one or moreimages for projecting. PDA 17 may comprise an image adjustment program,described below in more detail. Notably, projected image 16C isdistorted. Adjustment to remove or reduce this distortion is describedbelow in more detail. The PDA 17 may be incorporated into a projector14, or vice-versa

FIG. 1D is the pictorial view of FIG. 1C for a system portion and atop-down view of FIG. 1C for a projection portion. To a viewing audiencelocated in viewing position with respect to image surfaces 15C-1 and15C-2, projected image 16C appears as though projected on a virtualprojection screen 20. Adjustment to create this optical virtualprojection screen effect for projected image 16C is described below inmore detail.

For the remainder of this description, for purposes of clarity, only theimage projection system 10A will be described, but the remainder of thisdescription can be applied to any configuration.

FIG. 2A is a block diagram of an exemplary portion of an embodiment ofimage projection system 10A in accordance with one or more aspects ofthe present invention. Computer 18 comprises processor 22, system memory23, input/output (I/O) interface 24 and graphics subsystem 25. Processor22 is coupled to system memory 23, I/O interface 24. System memory 23may be programmed with all or a portion of a driver program 7 forexecuting instructions in accordance with one or more aspects of thepresent invention as described below in more detail.

I/O interface may be coupled to system memory 23 for direct memoryaddressing (DMA). Though computer 18 may be programmed to carry outgraphics oriented processing without a separate device for graphicsprocessing, a more efficient use of processor 22 is to have a separatedevice for graphics processing. Accordingly, graphics system 25 may becoupled to I/O interface 24 in a known manner. Such graphics subsystemsare well known, and often take the form of a “card.” Moreover, in someinstances, a graphics chip set is implemented on a motherboard, and thusno separate graphics card is used, or an optional separate graphics cardcan still be used, even if motherboard chips perform graphics functions.A key point is that no special circuitry for implementing one or moreaspects of the present invention is needed. Rather, one or more aspectsof the present invention may be implemented with “consumeroff-the-shelf” (COTS) equipment, such as a laptop and a CCD projector.This is an important advantage over systems requiring customized circuitdesigns or optics for image adjustment.

Graphics subsystem 25 may have an output 27 provided to projector 14.This output 27 may further optionally be provided to computer monitor11, namely, for same image display on multiple display surfaces.However, the block diagram of FIG. 2B is of an exemplary portion ofanother embodiment of image projection system 10A where graphicssubsystem 25 has separate outputs 26 and 27 for displaying same ordifferent images. Thus, an image from image output 27 may be provided toprojector 14 and a different image from image output 26 may be providedto computer monitor 11. Advantages associated with an ability to displaydifferent images will become more apparent as described below in moredetail.

FIG. 3 is a block diagram of an exemplary embodiment of a graphicspipeline 30 in accordance with one or more aspects of the presentinvention. Graphics pipelines are accessed by application programs viaan Application Program Interface (API), such as OpenGL®, D3D®, andDirect Draw®. For purposes of clarity, graphics pipeline 30 is describedas implemented in hardware, though a combination of hardware andsoftware may be used. Graphics pipeline comprises frontend 31, geometryprocessor 32, pixel processor 33, texture processor 34, rasteroperations processor 35, memory interface 36, memory or frame buffer 37,scan out processor 38, and optionally two-dimensional (2D) processor 47.Also, optionally texture processor may comprise a memory interface forcommunicating with a separate texture memory. Scan out processor 38 iscoupled to at least one display. So for example, a computer monitor or atelevision set may have a setup mode, where a displayed image isadjusted to a screen display. Handles, described below in more detail,may be provided to make one or more adjustments to such a displayedimage, such adjustments may include one or more of a pincushionadjustment, a trapezoid adjustment, a horizontal size adjustment, avertical size adjustment, a right pincushion adjustment, a leftpincushion adjustment, a right trapezoid adjustment, and a lefttrapezoid adjustment. Another example is a projected image that may beadjusted for one or more of the same types of adjustments. For reasonsthat will become more apparent with the detailed description thatfollows, it may be desirable to have separate outputs to respectivedisplays. Thus, scan out processor 38 may provide an output to display14, such as a projector, and another output to display 11, such as acomputer monitor.

With continuing reference to FIG. 3, and renewed reference to FIG. 2B,commands 39 are received from a host computer, such as computer 18, andsuch commands 39 may be made through a driver, such as driver 7 in FIGS.2A and 2B, for a graphics pipeline 30. That is, commands 39 are fed intothe graphics pipeline, producing an image 43, the image stored in memory3. Commands 39 may be in response to a program application, an operatingsystem or other computer program having an image to be displayed. So,for example, suppose commands 39 are to make an image characterized byimage data 43 to be stored in memory 37. That is, commands 39 are fedinto the graphics pipeline, producing an image 43, the image stored inmemory 37. Commands 39 may also indicate a range of addresses for memory37 in which to write generated image data 43. Furthermore, display lists39 may be used, which are commands that are bundled together and invokedby another command.

Commands 39 are provided to frontend 31, which manages DMA, bufferingcommands and the like for geometry processor 32. Geometry processor 32processes polygons and performs transforms, such as translation,scaling, rotation, field-of-view, and depth test near and far fieldclipping, among others, for such an image to be made. Pixel processor 33associates data to pixels for such an image 43 to be made.

Texture processor 34 generates texture values from texels stored astexture data 42, which texture data 42 can be stored in graphicssubsystem memory 37, texture memory 34M, or system memory 23. Textureprocessor 34 performs interpolation, including but not limited tonearest, bilinear, trilinear and anisotropic interpolation amongsttexels. Interpolation of texture coordinates, used to select texels forinterpolation, includes plane equation and barycentric. Because sometexel values are reused, texture processor 34 may cache texels to reducerepetitive reads from memory. Optionally, one or more coarserresolutions of image data 42 may be generated, for use in interpolation.

Raster operations processor 35 may blend, perform logic operations, andother known operations for such pixels. Memory interface 36 receivesimage data 43, in the form of pixel values and writes it to memory 37.Alternatively, commands 39 may be provided to 2D processor 47 togenerate image data 43 and store it in memory 37 via memory interface36.

Though image data 43 may be output for display 14 via memory interface36 and scan out processor 38, as instructed by a host computer 18, otheroperations for adjusting image data may be done with instruction fromhost computer 18 or without instruction by host computer 18, namely,“behind” an operating system of host computer 18. These operationsbehind the operating system are to provide at least one of a graphicuser interface and an adjustable image.

Texture data 42 is obtained from image data 43 and written to memory 37.Optionally, image data 43 may be copied for creation of texture data 42.

FIG. 9A is a block diagram of an exemplary embodiment of a computerscreen 11 having a screen image 100S displayed thereon in accordancewith one or more aspects of the present invention. Displayed with image101S is a graphical user interface (GUI) 200. This GUI 200 compriseshandles 101, optional handles 102, optional guide lines 111 and 112, andan optional center handle 107. When available, a user may select andmove center handle 107 to adjust for foreshortening, also referred tosometimes as anisotropic geometric distortion. Thus, center handle 107may be moved for anisotropic filtering. Alternatively, location of arelative center, namely, where corner-to-corner guide lines intersect,for an adjusted image may be done by calculation using adjustedlocations of points 94, 95, 96, and 97, but it is generally advantageousto have the center handle 107 positioned independently by the user.

To adjust a projected image, 16A, 16B and 16C, a user requests GUI 200be displayed on a computer desktop stored as image data 43. GUI 200allows the user to move or change position of handles 101, 102, 107,thereby adjusting display or projection of image data 43. Handles 101,102, 107 correspond to polygon vertices, so moving handles 101, 102, 107causes movement of such associated of vertices. Projected image 16A,16B, 16C is created by using image 43 of a computer desktop as a texturemap on the polygons. Moving handles moves vertices of associatedpolygons causing a stretching or shrinking of the displayed computerdesktop. Texture coordinates assigned to the vertices can be equal tothe corresponding (X,Y) location in the computer desktop beforeadjustment.

If both a monitor 11 and a projector 14 are present, display of GUI 200on computer screen of monitor 11 is optional. Accordingly, as it will beunderstood how a computer screen 11 may be adjusted with GUI 200, or aform thereof, in view of how a projected image is adjusted, it will beassumed that screen display 11 is not being adjusted. Rather, adjustmentof a projected image will be described, as adjusting a projected imagedescriptively covers adjusting a computer screen image.

Example, using FIG. 9A, assume computer screen 11 is in a 1600×1200resolution mode, though other well-known modes may be used. Vertices ofpolygons mapping screen image 100S are at points 94, 95, 96, 97, and 98with screen coordinates (0,0), (1599,0), (0,1199), (1599,1199), and(800,600), respectively. Cursor 106 is at screen coordinates (1300,1000)for purposes of example.

FIG. 9B is a block diagram of a projected image 100P of screen image100S of FIG. 9A onto an imaging surface 103, such as a screen, a wall ora whiteboard, among other types of surfaces. Projected image 100P is anunadjusted image.

FIG. 9C is a block diagram of projected image 100P of FIG. 9B afteradjustment in accordance with one or more aspects of the presentinvention. To adjust an image, a user selects a portion of an image tobe moved by selecting and moving or dragging a handle associated withthat portion. Selection and movement of handles may be done with amouse, a keyboard, a graphics tablet, a touch screen, or othercursor-pointing device. By way of example, to adjust projected image100P, handle 101A may be selected and dragged from location 104A tolocation 105A, and handle 101B may be selected and dragged from location104B to location 105B. Dashed lines are used to indicate position ofprojected image 100P prior to adjustment.

Adjustment of projected image 100P effects screen image 100S, asindicated in the block diagram of FIG. 9D. This is, if projector 14 andscreen 11 are displaying the same computer desktop or portion thereof,adjusting image 100P (projected by projector 14) to be rectangular willalso cause distortion of screen image 100S (as seen on screen 11). Inthe example of FIGS. 9E and 9D, by adjusting projected image 100P to berectangular, screen image 100S is keystoned or becomes trapezoidal.Continuing the above example, screen coordinates for points 94, 95, 96,97, and 98 are now (0,0), (1599,200), (0,1199), (1599,1100), and(1050,600), respectively. Cursor 106 is at screen coordinates(1300,1000) for purposes of example. Texture coordinates for points orvertices 94, 95, 96, 97, and 98 are (0,0), (1599,0), (0,1199),(1599,1199), and (800,600), respectively, as these are equal to the(X,Y) locations in the non-adjusted image 43 or texture data 42 if theimage 43 has been copied to a different location as a texture map.However, adjusting image data 43 (e.g., a computer desktop) will cause adifferent mapping between pixel locations and any icon that appearswithin the image 43. For example, if a button is displayed on anadjusted image 100S, and a user moves a mouse pointer 106 to point atthe button, the mouse click that sends the (X,Y) location of the pointerwithin the display 11 will be wrong. Therefore, the true pointerlocation must be determined. To determine the location of cursor 106,the texture coordinates of triangle 110 are interpolated to determinetexture coordinates (S,T) using barycentric coordinates or a planeequation as shown in FIG. 10.

FIG. 9E is a block diagram of screen image 100S-1 after adjustment ofprojected image 100P and after turning off GUI 200. However, screenimage 100S-1 of FIG. 9E is screen image 100S of FIG. 9A and not screenimage 100S of FIG. 9D. This may be done by having scan out processor 38with separate outputs and a stored unadjusted version of image data 43to display. Moreover, toggling between screen images 100S and 100S-1 maybe done by a user with selection of a key on a keyboard, such as afunction key.

FIG. 9F is a block diagram of projected image 100P after adjustment andafter turning off GUI 200. Notably, positions of cursors 106 in FIGS. 9Eand 9F track with one another. However, because an adjusted image hasdifferent screen coordinates than an unadjusted image, a cursor trackingroutine is used to allow display of adjusted and unadjusted images witha common cursor, including common cursor movement. That is, scan outprocessor 38 can have two hardware cursors.

With continuing reference to FIGS. 9A through 9F and renewed referenceto FIGS. 2B and 3, as previously described, image data 43 comprisesmapping of polygons, where each polygon has vertices. Coordinates ofthese vertices, or coordinates related to these vertices, are stored astexture coordinates. These texture coordinates are held constant thoughscreen coordinates of image data 43 are changed by adjustment ofprojected image 100P.

FIGS. 3A and 3B are block diagrams of an exemplary embodiment of agraphics pipeline coupled to two displays receiving separate scanoutputs in accordance with one or more aspects of the present invention.With continuing reference to FIGS. 3A and 3B, and renewed reference toFIGS. 2B, 3, and 9A through 9F, in response to a user moving at leastone handle of handles 101, 102 or 107, geometry commands 49 are providedto frontend 31, as indicated by dashed line 201. Geometry processor 32in response to geometry commands 49 redraws polygons for a new screenimage to be generated, for example adjusted screen image of FIG. 9D.Image data 43 (being the non-adjusted image data) is retrieved frommemory 37 (where the image of the computer desktop is stored andaccessible as a texture) and provided to texture processor 34, asindicated by dashed line 202. Alternatively, texture data 42 may be usedinstead of image data 43, if image data is converted to texture data.Pixel processor 33 receives texture information, as indicated by dashedline 202, from texture processor 34 and polygon data from geometryprocessor 32, as indicated by dashed line 201, and provides pixels foran adjusted image. These pixels may have other known raster operationsdone to them by raster operations processor 35, and are stored intoscreen image data 41, as indicated by dashed line 201. Screen image data41 is an adjusted or warped image as indicated in FIG. 9D; however, thisadjusted screen image data 41 is provided to scan out processor 38 foroutput to projector 14 for projection as an adjusted image, for exampleas in FIG. 9F and as indicated by dashed line 203. In other words, auser can adjust or warp an image using GUI 200 to provide and adjustedor unwarped projected image.

With separate outputs from scan output processor 38, an unadjustedversion of image data 43 may be provided to scan out processor 38 fordisplay on computer monitor 11 in order to provide an unwarped screenimage, for example as in FIG. 9E and as indicated by dashed line 204.However, because screen image data 41 has different screen coordinatesthan image data 43, cursor tracking may be used to avoid informing anoperating system of an incorrect cursor position. Alternatively, eitherscreen image data 41 or image data 43 may be used as a cursor controlscreen for informing an operating system of position of cursor 106.Alternatively, a cursor may be treated like an overlay where a blocktransfer is used, as described below in more detail.

FIG. 4 is a process flow diagram of an exemplary embodiment of a displayimage adjustment process 50 in accordance with one or more aspects ofthe present invention. At step 51, image data is obtained (e.g., anoperating system and/or application programs generate commands thatcreate a computer desktop image). At step 52, image data obtained ismapped with polygons (e.g., a plurality of polygons that have thecomputer desktop as a texture, each polygon vertex having a texturecoordinate in the computer desktop image texture). At step 53, handlesassociated with such polygons are provided as part of a display output(e.g., a handle is displayed at each polygon vertex, polygons that sharea vertex share a corresponding handle). At step 54, a user moves one ormore handles to provide user input (e.g. using a GUI the user reducesthe projection distortion of the computer desktop). At step 55,locations are adjusted in response to such user input (e.g., thelocations of the vertices are moved, thereby changing the shape of thepolygons). At step 56, an adjusted image is made with adjusted locationsfor image data (e.g., the polygons are rendered using the new vertexlocations, creating an adjusted image). At step 57, an adjusted image isoutput for display (e.g., the rendered polygons are displayed).

FIG. 5 is a process flow diagram of an exemplary embodiment of a displayimage adjustment process 60 in accordance with one or more aspects ofthe present invention. At step 61, image data is received (e.g.,commands and/or pixels), and such image data received is stored at step62. At step 63, stored image data is stored as texture (this can besimply accessing the stored image as a texture, thereby eliminatingrestoring of data). Stored texture is mapped with polygons at step 64.At step 65, at least a portion of polygon vertices from step 64 areoutput for display as handles. At step 66, a user inputs imageadjustment data by selecting and moving handles provided at step 65. Atstep 67, polygon vertices output as handles and moved by a user areadjusted in response to such user movement of the handles. At step 68,an adjusted image is generated by rendering polygons with adjustedvertices from step 67 using such texture stored at step 63. At step 69,an adjusted image from step 68 is output for display.

FIG. 6 is a process flow diagram of an exemplary embodiment of a displayimage adjustment process 70 in accordance with one or more aspects ofthe present invention. At step 71, image data and overlay data isreceived. It should be appreciated that overlay data may be providedfrom a decoder, such as a video decoder 48, to memory 37, as shown inFIG. 3. Additionally, a cursor is a type of overlay, and may be handledin a similar manner. However, for purposes of clarity, overlay data isdescribed as a video overlay. At step 72, image data and overlay dataare stored. At step 73, image data is stored as texture. At step 74,overlay data is copied into texture. This may be done by a blocktransfer (BLT). At step 75, image data is mapped with polygons. At step76, handles are output, where such handles are associated with verticesof mapped polygons at step 75. At step 77, a user provides imageadjustment information by moving one or more handles output at step 76.At step 78, one or more vertices are adjusted for a screen image inresponse to user input from step 77. A centrally located handle may beoutput at step 76 for user movement at step 77 for adjustment of adisplayed image. At step 79, an adjusted image is generated by renderingpolygons with adjusted vertices from step 78 using image data stored astexture at step 73 and overlay data copied into texture at step 74. Atstep 88, an adjusted image with an overlay is output for display. Itshould be understood that an overlay image is also adjusted in responseto user input as such overlay was converted to texture.

FIG. 7 is a process flow diagram of an exemplary embodiment of a displayimage adjustment process 80 in accordance with one or more aspects ofthe present invention. At step 71, image data and overlay data areobtained. At step 72, image data and overlay data is stored. At step 73,image data is stored as texture. At step 81, image data stored astexture at step 73 is mapped with polygons. At step 82, handlesassociated with vertices of mapped polygons are output. At step 83, userinput image adjustment information, from moving one or more handles, isobtained. At step 84, one or more vertices are adjusted for a screenimage in response to user input obtained at step 83. A centrally locatedhandle may be output at step 82 for user movement input at step 83 foranisotropic adjustment of a displayed image. At step 85, an adjustedimage is generated by rendering polygons with adjusted vertices of step84. At step 86, vertices for such an overlay image stored at step 72 areadjusted corresponding to adjustment at step 84 for a screen image. Itshould be understood that overlay data is being treated as a separatetexture rendered onto separate polygons. At step 87, an adjusted overlayimage is generated by rendering it with polygons with adjusted verticesfrom step 86. At step 89, an adjusted image with an adjusted overlay isoutput for display.

Another approach to an overlay would be to provide handles as isdescribed above for an image to be adjusted. However, tracking withoutspecialized hardware may impact speed.

A cursor may be treated as an overlay as described above; however, withrenewed reference to FIG. 3, a conventional scan out processor 38comprises cursor hardware 45 including cursor register 46. Cursorhardware 45 receives incoming pixel information and determines whichpixels to overlay or substitute cursor pixels stored in cursor hardware45 based on cursor location stored in cursor register 46. This speeds upcursor operation.

FIG. 8 is a process flow diagram of an exemplary embodiment of a cursortracking routine 90 in accordance with one or more aspects of thepresent invention. At step 91, X and Y coordinates for adjusted screenimage are obtained. At step 92, S and T coordinates in a texture map aredetermined. S and T may be determined by interpolation from X and Ycoordinates obtained in step 91 with vertex coordinates for a polygon inwhich a cursor is located. This may be done with barycentricinterpolation or plane equation partial derivatives. At step 93, S and Tcoordinates are provided to a host computer, such as computer 18,operating system as cursor position. Notably, cursor tracking routine 90is reversible, namely, if S and T coordinates are obtained at step 91,then X and Y coordinates may be determined at step 92 and output ascursor position at step 93. Accordingly, it depends on which image,namely, a project image or a computer screen display image, is selectedas a reference display. Moreover, screen coordinates for an unadjustedimage, for example stored image 43 of FIG. 3, may be determined in asimilar manner or used to determine texture coordinates, again dependingon what is the reference display.

Continuing the above example, FIG. 10 is an enlarged version of adjustedpolygon 110 of FIG. 9D, namely, a portion of an adjusted computer screenimage. Notably, though polygon 110 is a triangle, other known types ofpolygons for computer graphics may be used. Point or vertex 96 hasscreen X- and Y-coordinates (0,1199) and texture S- and T-coordinates(0,1199). Vertex 97 has screen X- and Y-coordinates (1599,1100) andtexture S- and T-coordinates (1599,1199). Vertex 98 has screen X- andY-coordinates (1050,600) and texture S- and T-coordinates (800,600).Accordingly, texture coordinates are unchanged by one or more changes inadjusted image screen coordinates. Moreover, cursor position on a screenis determinable, in this example cursor vertex 106 has screen X- andY-coordinates (1300,1000). Interpolation may be used to findcorresponding texture coordinates S and T to X- and Y-coordinates(1300,1000) at point 106.

With renewed reference to FIG. 3, for a dual cursor embodiment, both Xand Y screen coordinates and S and T texture coordinates are stored incursor register 46. S and T texture coordinate located cursor image isprovided as output to projector 14, and X and Y screen coordinatelocated cursor image is provided as output to computer monitor 11.Notably, both sets of X and Y screen coordinates, namely, for anunadjusted image coordinates (X_(u),Y_(u)) such as for image data 43 oran adjusted image coordinates (X_(a),Y_(a)) such as for FIG. 9D, may bestored in cursor register memory 46 and used for toggling betweenunadjusted and adjusted images on computer monitor 11.

Some embodiments of the present invention are program products that mayreside in whole or in part in memory. By way of example and notlimitation, memory may be sufficient to hold at least a portion of oneor more of process 50, 60, 70, 80, and 90 in accordance with one or moreembodiments of the present invention. Memory may comprise volatileand/or non-volatile memory, including but not limited to magneticallyreadable memory (e.g., floppy disk, hard disk, and the like), opticallyreadable memory (e.g., CD-ROM, -RW, DVD-ROM, -RAM, and the like), andelectrically readable memory (e.g., DRAM, SRAM, EEPROM, registers,latches, and the like). Accordingly, some embodiments of the inventionare program products containing machine-readable programs. Theprogram(s) of the program product defines functions of the embodimentsand can be contained on a variety of signal/bearing media, whichinclude, but are not limited to: (i) information permanently stored onnon-writable storage media (e.g., read-only memory devices within acomputer such as CD-ROM disks readable by a CD-ROM drive); and (ii)alterable information stored on writable storage media (e.g., floppydisks within a diskette drive or hard-disk drive).

Notably, number of handles displayed may be increased or decreaseddepending on projector setup. For example, if a projector is always setto one side of a room, fewer handles may be displayed, and if an imagingsurface is more complex than a planar screen, such as a cylinder or asphere, then more handles may be displayed. Thus, a user may berequested to select a type of surface, if other than a default planarsurface. One type of surface a user may select may actually involve morethan one surface, such as projection into a corner between two walls.

FIG. 11 is a block diagram of an exemplary embodiment of a corneradjustment GUI 120 in accordance with one or more aspects of the presentinvention. Corner adjustment GUI 120 comprises at least six handles 121,122 and 129. Corner adjustment GUI 120 may further comprise one or moreof optional handles 123, optional corner guide line 128 extendingbetween handles 122, optional guide lines 124, 125, 126 and 127diagonally extending between handles 121, 122 and 129, and optionalguide lines 131 through 136 forming a perimeter. Handles 122 dividecorner adjustment GUI 120 into two surface projection portions.

FIG. 12A is a perspective view of a corner projection 130 with corneradjustment GUI 120 and an unadjusted image in accordance with one ormore aspects of the present invention. FIG. 12B is a perspective view ofcorner projection 130 with corner adjustment GUI 120 and an adjustedimage in accordance with one or more aspects of the present invention.Notably, such an adjusted image will appear to a viewer as imaging on avirtual screen, as described above. Having an ability to project ontomultiple planar surfaces increases likelihood of projecting an imagesufficiently large and positioned for viewing by an audience.

While the above description has been in terms of a computer monitor anda portable projector in some embodiments, it should be understood thatother embodiments may be used. For example, rather than a computermonitor or a portable projector, a digital theater projector, a heads-updisplay, cell phone display, a portable game display, a GPS, anautomotive display and the like, among other types of displays may beused. In particular, projectors may be adjusted to compensate forprojected off-center distortion or lens magnified-distortion, such asfor a micro-LCD. Moreover, integrated chip scale displays for mobilesystems may be adjusted. Furthermore, cable, satellite and home theatersetup may employ adjustment in accordance with one or more aspects ofthe present invention for a digital television or monitor. Othersurfaces that may be used for projection include mist, a curvedwindshield and the like. Additionally, as television broadcasts,especially sports, are limited to certain field-of-views, though limited“reverse angle” viewing is available, the present invention may be usedto mix a digital image to adjust imagery for different field-of-views.

It should be appreciated that keystone (trapezium) and focal pointadjustment in accordance with one or more aspects of the presentinvention may be used for perceptibly real-time adjustment with fidelityto the original image, namely, with perceivably lossless picturequality. Real-time adjustment compensation is useful for 3D and highframe rate digital projection.

It should be appreciated that embodiments of the present inventionoperate independently of projection platform. Thus, wide spreaddeployment is facilitated by cross-platform usage.

Furthermore, it should be appreciated that pixel shading in a graphicdisplay may be adjusted with one or more embodiments of the presentinvention. In addition to shading, other known features in a graphicimage may be independently adjusted.

While foregoing is directed to the preferred embodiment of the presentinvention, other and further embodiments of the invention may be devisedwithout departing from the basic scope thereof, and the scope thereof isdetermined by the claims that follow. All trademarks are the respectiveproperty of their owners. Claims listing steps do not imply any order ofthe steps.

1. A computer-implemented method for adjusting a displayed image,comprising: obtaining first image content; storing the first imagecontent as a texture that includes a set of texels in a graphicssubsystem memory; displaying a first image on a display device based onthe first image content; applying at least one polygon to the firstimage content, wherein the at least one polygon is not a part of thefirst image content and includes a set of vertices that is associatedwith texture coordinates in the texture; displaying a set of handles onthe first image as moveable objects, wherein at least one of themoveable objects is located to indicate a focal point of the first imageand is manipulated for counteracting distortion of the first imagecaused by an off-set projection of the first image, and wherein a firsthandle in the set of handles is associated with a first vertex in theset of vertices; receiving a modification to the first handle; updatinga location of the first handle in response to the modification; changinga location of the first vertex in response to updating the location ofthe first handle; changing the texture coordinates in response tochanging the location of the first vertex; generating second imagecontent based on changing the texture coordinates; and displaying asecond image on the display device based on the second image content. 2.The method of claim 1, wherein display device is a screen display. 3.The method of claim 1, wherein display the first image comprisesprojecting the first image.
 4. The method of claim 3, wherein the firstimage is projected onto a planar surface.
 5. The method of claim 3,wherein the first image is projected onto a spherical surface.
 6. Themethod of claim 3, wherein the first image is projected onto acurvilinear surface.
 7. The method of claim 3, wherein the first imageis projected onto a vapor.
 8. The method of claim 3, wherein the firstimage is projected onto a photon-reactive gas.
 9. The method of claim 1,wherein the set of handles includes at least five handles associatedwith at least five different vertices, four of the at least fivevertices associated with four corners of the texture, and one of the atleast five vertices associated with a texture coordinate centrallylocated with respect to the texture.
 10. The method of claim 1, whereinthe moveable objects are located at least proximal to image boundariesof the first image.
 11. The method of claim 10, wherein the moveableobjects are located at least proximal to sides of the first image. 12.The method of claim 10, wherein the moveable objects are located atleast proximal to corners of the first image.
 13. A computer-implementedmethod for adjusting for anisotropic distortion, comprising: obtainingfirst image content; storing the first image content as a texture thatincludes a set of texels in a graphics subsystem memory; displaying anunadjusted image on a display device based on the first image content;rendering polygons onto the unadjusted image, wherein the polygons arenot a part of the unadjusted image and include a set of vertices that isassociated with texture coordinates in the texture, and wherein thepolygons are manipulated for counteracting distortion of the unadjustedimage due caused by an off-set projection of the first image, and;selecting a first vertex associated with a corner of the unadjustedimage; moving the first vertex to provide an adjusted image; calculatinga center of the adjusted image in response to moving the first vertex;adjusting the adjusted image for anisotropic distortion in response tothe center calculated; and displaying the adjusted image on the displaydevice.
 14. A system for adjusting a displayed image, the systemcomprising: a processor; a display device; and a memory configured tostore an application that includes instructions which, when executed bythe processor, cause the processor to perform operations for adjustingthe displayed image, by performing the steps of: storing the first imagecontent as a texture that includes a set of texels, displaying a firstimage on the display device based on the first image content, applyingat least one polygon to the first image content, wherein the at leastone polygon is not a part of the first image content and includes a setof vertices that is associated with texture coordinates in the texture,displaying a set of handles on the first image, wherein the set ofhandles is displayed on the first image as moveable objects, at leastone of the moveable objects is located to indicate a focal point of thefirst image and is manipulated for counteracting distortion of the firstimage due caused by an off-set projection of the first image, andwherein a first handle in the set of handles is associated with a firstvertex in the set of vertices, receiving a modification to the firsthandle, updating a location of the first handle in response to themodification, changing a location of the first vertex in response toupdating the location of the first handle, changing the texturecoordinates in response to changing the location of the first vertex,generating second image content based on changing the texturecoordinates, and displaying a second image on the display device basedon the second image content.